Appendix C. Cache and Cache Page Size

Appendix C. Cache and Cache Page Size
Prev		Next

This appendix contains information on read cache and write cache size, cache page size, and storage processor revision level.

The amount of write cache you can allocate depends on the SP revision level. To determine the revision level of an SP, open the door of the storage system and observe the label on the SP panel; see Figure C-1.

Figure C-1. Determining SP Revision Level from SP Label

Another way to determine SP revision level is to enter

scsicontrol -I devicename

In the output, look for the numerals 00 or 01 at the right, as pointed out in Figure C-2.

Figure C-2. Determining SP Revision Level From scsicontrol -I Output

In this output, 00 corresponds to 9470198 and 01 corresponds to 9470284 (formerly 9470207).

Table C-1 and Table C-2 show the relationships between cache page size and cache configuration for each revision level of SP.

Table C-1. Cache Capability for SP 9470198

Cache Page Size	User-Configurable Write Cache	User-Configurable Read Cache	Cache Configuration
2 KB	14 MB 0 7 MB	0 21 MB 7 MB	100% write cache 100% read cache 50% write/50% read
4 KB	28 MB 0 14 MB	0 43 MB 14 MB	100% write cache 100% read cache 50% write/50% read
8 KB	56 MB 0 28 MB	0 86 MB 28 MB	100% write cache 100% read cache 50% write/50% read
16 KB	113 MB 0 56 MB	0 120 MB 56 MB	100% write cache 100% read cache 50% write/50% read

Table C-2. Cache Capability for SP 9470284

Cache Page Size	User-Configurable Write Cache	User-Configurable Read Cache	Cache Configuration
2 KB	194 MB 0 106 MB	0 248 MB 106 MB	100% write cache 100% read cache 50% write/50% read
4 KB	388 MB 0 213 MB	0 497 MB 213 MB	100% write cache 100% read cache 50% write/50% read
8 KB	504 MB 0 426 MB	0 504 MB 426 MB	100% write cache 100% read cache 50% write/50% read
16 KB	504 MB 0 504 MB	0 504 MB 504 MB	100% write cache 100% read cache 50% write/50% read

Prev	Table of Contents	Next
Appendix B. Server Serial Connector Pinouts		Index